The footage is from Barstow, Calif. The police are called to a traffic incident in a school parking lot. A white woman complains to the police about the incident. She claims that another woman had acted "crazy" and had "punched my window." The window isn't damaged.

At first, the officer offers: "I don't see a crime that has been committed." Everything seems polite and controlled.

He then walks over to a second woman, Charlena Cooks. She is black and, at the time of the incident, was 8 months pregnant. She describes her version of the incident. She denies having thrown anything at the other woman's car.

Everything seems reasonable until the police officer asks Cooks for her name. He hadn't, at least according to the footage, asked the white woman's name. Cooks refuses to give her name.

"I do have the right to ask you," says the officer. He was correct, but there is no law that says Cooks had to tell him her name.

Cooks wants to make a call to make sure the officer is telling the truth. Suddenly, the officer declares: "Ma'am. I'm going to give you two minutes."

The officer becomes insistent. In an instant, he grabs Cooks, as she pleads with him not to touch her. She is handcuffed behind her back and then cast to the ground.

ACLU attorney Jessica Price told me that the footage came to light after the Barstow police had arrested two brothers, Jesse and Robert Katz in 2014. They had been accused of stealing a vaporizer in a taco restaurant.

The ACLU took up their case, as the Katz brothers had also been arrested for refusing to give their ID. Last week, the ACLU and the City of Barstow reached a negotiated conclusion, which involved compensation being paid and the promise that the local police would undergo new training so that they understood the law.

In Cooks's case, the police voluntarily produced the footage, Price told me, because they said it proved that Cooks had resisted arrest by taking a step back.

How odd that stepping back would signify resistance as opposed to, say, fear. Still, the police proceeded. This was until, Price said, "the prosecution realized it had no law on which to base its case."

She added: "They handcuffed a pregnant woman behind her back. They threw her to the ground. This was a woman who had come to pick up her second-grade daughter from school."

Price, who doesn't represent Cooks, told me that she doesn't believe that this assumption that refusing to give your ID constitutes obstruction is limited to Barstow.

Initially, the police issued a statement, reported by CBS Los Angeles, that included these words: "It is apparent that Ms. Cook actively resisted arrest."

What might be apparent to some is that the officers treated an innocent black woman very differently from the way they had treated an innocent white one.

More Technically Incorrect

When I contacted Barstow police, Lt. Michael Hunter told me: "The incident is being investigated and we have no further comment."

The case was dismissed last month and I understand that Cooks is now pursuing a claim for damages against the Barstow police department.

How odd, though, that footage that seems so clear could be subject to such differing interpretation. Whenever cases such as this appear, it's not a suggestion that every police officer behaves this way. It's a difficult job, as many officers have to suffer awful and sometimes deadly behavior from members of the public.

This is the future, though. One in which footage will be parsed with differing interpretations. At least the footage is there for all to see.